import re
import getpass
import sys
import os
import mimetypes
import shutil
import tempfile
from pip.backwardcompat import (md5, copytree, xmlrpclib, urllib, urllib2,
                                urlparse, string_types, HTTPError)
from pip.exceptions import InstallationError
from pip.util import (splitext, rmtree,
                      format_size, display_path, backup_dir, ask,
                      unpack_file, create_download_cache_folder, cache_download)
from pip.vcs import vcs
from pip.log import logger


__all__ = ['xmlrpclib_transport', 'get_file_content', 'urlopen',
           'is_url', 'url_to_path', 'path_to_url', 'path_to_url2',
           'geturl', 'is_archive_file', 'unpack_vcs_link',
           'unpack_file_url', 'is_vcs_url', 'is_file_url', 'unpack_http_url']


xmlrpclib_transport = xmlrpclib.Transport()


def get_file_content(url, comes_from=None):
    """Gets the content of a file; it may be a filename, file: URL, or
    http: URL.  Returns (location, content)"""
    match = _scheme_re.search(url)
    if match:
        scheme = match.group(1).lower()
        if (scheme == 'file' and comes_from
            and comes_from.startswith('http')):
            raise InstallationError(
                'Requirements file %s references URL %s, which is local'
                % (comes_from, url))
        if scheme == 'file':
            path = url.split(':', 1)[1]
            path = path.replace('\\', '/')
            match = _url_slash_drive_re.match(path)
            if match:
                path = match.group(1) + ':' + path.split('|', 1)[1]
            path = urllib.unquote(path)
            if path.startswith('/'):
                path = '/' + path.lstrip('/')
            url = path
        else:
            ## FIXME: catch some errors
            resp = urlopen(url)
            return geturl(resp), resp.read()
    try:
        f = open(url)
        content = f.read()
    except IOError:
        e = sys.exc_info()[1]
        raise InstallationError('Could not open requirements file: %s' % str(e))
    else:
        f.close()
    return url, content


_scheme_re = re.compile(r'^(http|https|file):', re.I)
_url_slash_drive_re = re.compile(r'/*([a-z])\|', re.I)

class URLOpener(object):
    """
    pip's own URL helper that adds HTTP auth and proxy support
    """
    def __init__(self):
        self.passman = urllib2.HTTPPasswordMgrWithDefaultRealm()

    def __call__(self, url):
        """
        If the given url contains auth info or if a normal request gets a 401
        response, an attempt is made to fetch the resource using basic HTTP
        auth.

        """
        url, username, password = self.extract_credentials(url)
        if username is None:
            try:
                response = urllib2.urlopen(self.get_request(url))
            except urllib2.HTTPError:
                e = sys.exc_info()[1]
                if e.code != 401:
                    raise
                response = self.get_response(url)
        else:
            response = self.get_response(url, username, password)
        return response

    def get_request(self, url):
        """
        Wraps the URL to retrieve to protects against "creative"
        interpretation of the RFC: http://bugs.python.org/issue8732
        """
        if isinstance(url, string_types):
            url = urllib2.Request(url, headers={'Accept-encoding': 'identity'})
        return url

    def get_response(self, url, username=None, password=None):
        """
        does the dirty work of actually getting the rsponse object using urllib2
        and its HTTP auth builtins.
        """
        scheme, netloc, path, query, frag = urlparse.urlsplit(url)
        req = self.get_request(url)

        stored_username, stored_password = self.passman.find_user_password(None, netloc)
        # see if we have a password stored
        if stored_username is None:
            if username is None and self.prompting:
                username = urllib.quote(raw_input('User for %s: ' % netloc))
                password = urllib.quote(getpass.getpass('Password: '))
            if username and password:
                self.passman.add_password(None, netloc, username, password)
            stored_username, stored_password = self.passman.find_user_password(None, netloc)
        authhandler = urllib2.HTTPBasicAuthHandler(self.passman)
        opener = urllib2.build_opener(authhandler)
        # FIXME: should catch a 401 and offer to let the user reenter credentials
        return opener.open(req)

    def setup(self, proxystr='', prompting=True):
        """
        Sets the proxy handler given the option passed on the command
        line.  If an empty string is passed it looks at the HTTP_PROXY
        environment variable.
        """
        self.prompting = prompting
        proxy = self.get_proxy(proxystr)
        if proxy:
            proxy_support = urllib2.ProxyHandler({"http": proxy, "ftp": proxy})
            opener = urllib2.build_opener(proxy_support, urllib2.CacheFTPHandler)
            urllib2.install_opener(opener)

    def parse_credentials(self, netloc):
        if "@" in netloc:
            userinfo = netloc.rsplit("@", 1)[0]
            if ":" in userinfo:
                return userinfo.split(":", 1)
            return userinfo, None
        return None, None

    def extract_credentials(self, url):
        """
        Extracts user/password from a url.

        Returns a tuple:
            (url-without-auth, username, password)
        """
        if isinstance(url, urllib2.Request):
            result = urlparse.urlsplit(url.get_full_url())
        else:
            result = urlparse.urlsplit(url)
        scheme, netloc, path, query, frag = result

        username, password = self.parse_credentials(netloc)
        if username is None:
            return url, None, None
        elif password is None and self.prompting:
            # remove the auth credentials from the url part
            netloc = netloc.replace('%s@' % username, '', 1)
            # prompt for the password
            prompt = 'Password for %s@%s: ' % (username, netloc)
            password = urllib.quote(getpass.getpass(prompt))
        else:
            # remove the auth credentials from the url part
            netloc = netloc.replace('%s:%s@' % (username, password), '', 1)

        target_url = urlparse.urlunsplit((scheme, netloc, path, query, frag))
        return target_url, username, password

    def get_proxy(self, proxystr=''):
        """
        Get the proxy given the option passed on the command line.
        If an empty string is passed it looks at the HTTP_PROXY
        environment variable.
        """
        if not proxystr:
            proxystr = os.environ.get('HTTP_PROXY', '')
        if proxystr:
            if '@' in proxystr:
                user_password, server_port = proxystr.split('@', 1)
                if ':' in user_password:
                    user, password = user_password.split(':', 1)
                else:
                    user = user_password
                    prompt = 'Password for %s@%s: ' % (user, server_port)
                    password = urllib.quote(getpass.getpass(prompt))
                return '%s:%s@%s' % (user, password, server_port)
            else:
                return proxystr
        else:
            return None

urlopen = URLOpener()


def is_url(name):
    """Returns true if the name looks like a URL"""
    if ':' not in name:
        return False
    scheme = name.split(':', 1)[0].lower()
    return scheme in ['http', 'https', 'file', 'ftp'] + vcs.all_schemes


def url_to_path(url):
    """
    Convert a file: URL to a path.
    """
    assert url.startswith('file:'), (
        "You can only turn file: urls into filenames (not %r)" % url)
    path = url[len('file:'):].lstrip('/')
    path = urllib.unquote(path)
    if _url_drive_re.match(path):
        path = path[0] + ':' + path[2:]
    else:
        path = '/' + path
    return path


_drive_re = re.compile('^([a-z]):', re.I)
_url_drive_re = re.compile('^([a-z])[:|]', re.I)


def path_to_url(path):
    """
    Convert a path to a file: URL.  The path will be made absolute.
    """
    path = os.path.normcase(os.path.abspath(path))
    if _drive_re.match(path):
        path = path[0] + '|' + path[2:]
    url = urllib.quote(path)
    url = url.replace(os.path.sep, '/')
    url = url.lstrip('/')
    return 'file:///' + url


def path_to_url2(path):
    """
    Convert a path to a file: URL.  The path will be made absolute and have
    quoted path parts.
    """
    path = os.path.normpath(os.path.abspath(path))
    drive, path = os.path.splitdrive(path)
    filepath = path.split(os.path.sep)
    url = '/'.join([urllib.quote(part) for part in filepath])
    if not drive:
        url = url.lstrip('/')
    return 'file:///' + drive + url


def geturl(urllib2_resp):
    """
    Use instead of urllib.addinfourl.geturl(), which appears to have
    some issues with dropping the double slash for certain schemes
    (e.g. file://).  This implementation is probably over-eager, as it
    always restores '://' if it is missing, and it appears some url
    schemata aren't always followed by '//' after the colon, but as
    far as I know pip doesn't need any of those.
    The URI RFC can be found at: http://tools.ietf.org/html/rfc1630

    This function assumes that
        scheme:/foo/bar
    is the same as
        scheme:///foo/bar
    """
    url = urllib2_resp.geturl()
    scheme, rest = url.split(':', 1)
    if rest.startswith('//'):
        return url
    else:
        # FIXME: write a good test to cover it
        return '%s://%s' % (scheme, rest)


def is_archive_file(name):
    """Return True if `name` is a considered as an archive file."""
    archives = ('.zip', '.tar.gz', '.tar.bz2', '.tgz', '.tar', '.pybundle')
    ext = splitext(name)[1].lower()
    if ext in archives:
        return True
    return False


def unpack_vcs_link(link, location, only_download=False):
    vcs_backend = _get_used_vcs_backend(link)
    if only_download:
        vcs_backend.export(location)
    else:
        vcs_backend.unpack(location)


def unpack_file_url(link, location):
    source = url_to_path(link.url)
    content_type = mimetypes.guess_type(source)[0]
    if os.path.isdir(source):
        # delete the location since shutil will create it again :(
        if os.path.isdir(location):
            rmtree(location)
        copytree(source, location)
    else:
        unpack_file(source, location, content_type, link)


def _get_used_vcs_backend(link):
    for backend in vcs.backends:
        if link.scheme in backend.schemes:
            vcs_backend = backend(link.url)
            return vcs_backend


def is_vcs_url(link):
    return bool(_get_used_vcs_backend(link))


def is_file_url(link):
    return link.url.lower().startswith('file:')


def _check_md5(download_hash, link):
    download_hash = download_hash.hexdigest()
    if download_hash != link.md5_hash:
        logger.fatal("MD5 hash of the package %s (%s) doesn't match the expected hash %s!"
                     % (link, download_hash, link.md5_hash))
        raise InstallationError('Bad MD5 hash for package %s' % link)


def _get_md5_from_file(target_file, link):
    download_hash = md5()
    fp = open(target_file, 'rb')
    while 1:
        chunk = fp.read(4096)
        if not chunk:
            break
        download_hash.update(chunk)
    fp.close()
    return download_hash


def _download_url(resp, link, temp_location):
    fp = open(temp_location, 'wb')
    download_hash = None
    if link.md5_hash:
        download_hash = md5()
    try:
        total_length = int(resp.info()['content-length'])
    except (ValueError, KeyError):
        total_length = 0
    downloaded = 0
    show_progress = total_length > 40*1000 or not total_length
    show_url = link.show_url
    try:
        if show_progress:
            ## FIXME: the URL can get really long in this message:
            if total_length:
                logger.start_progress('Downloading %s (%s): ' % (show_url, format_size(total_length)))
            else:
                logger.start_progress('Downloading %s (unknown size): ' % show_url)
        else:
            logger.notify('Downloading %s' % show_url)
        logger.debug('Downloading from URL %s' % link)

        while 1:
            chunk = resp.read(4096)
            if not chunk:
                break
            downloaded += len(chunk)
            if show_progress:
                if not total_length:
                    logger.show_progress('%s' % format_size(downloaded))
                else:
                    logger.show_progress('%3i%%  %s' % (100*downloaded/total_length, format_size(downloaded)))
            if link.md5_hash:
                download_hash.update(chunk)
            fp.write(chunk)
        fp.close()
    finally:
        if show_progress:
            logger.end_progress('%s downloaded' % format_size(downloaded))
    return download_hash


def _copy_file(filename, location, content_type, link):
    copy = True
    download_location = os.path.join(location, link.filename)
    if os.path.exists(download_location):
        response = ask('The file %s exists. (i)gnore, (w)ipe, (b)ackup '
                       % display_path(download_location), ('i', 'w', 'b'))
        if response == 'i':
            copy = False
        elif response == 'w':
            logger.warn('Deleting %s' % display_path(download_location))
            os.remove(download_location)
        elif response == 'b':
            dest_file = backup_dir(download_location)
            logger.warn('Backing up %s to %s'
                        % (display_path(download_location), display_path(dest_file)))
            shutil.move(download_location, dest_file)
    if copy:
        shutil.copy(filename, download_location)
        logger.indent -= 2
        logger.notify('Saved %s' % display_path(download_location))


def unpack_http_url(link, location, download_cache, only_download):
    temp_dir = tempfile.mkdtemp('-unpack', 'pip-')
    target_url = link.url.split('#', 1)[0]
    target_file = None
    download_hash = None
    if download_cache:
        target_file = os.path.join(download_cache,
                                   urllib.quote(target_url, ''))
        if not os.path.isdir(download_cache):
            create_download_cache_folder(download_cache)
    if (target_file
        and os.path.exists(target_file)
        and os.path.exists(target_file+'.content-type')):
        fp = open(target_file+'.content-type')
        content_type = fp.read().strip()
        fp.close()
        if link.md5_hash:
            download_hash = _get_md5_from_file(target_file, link)
        temp_location = target_file
        logger.notify('Using download cache from %s' % target_file)
    else:
        resp = _get_response_from_url(target_url, link)
        content_type = resp.info()['content-type']
        filename = link.filename
        ext = splitext(filename)[1]
        if not ext:
            ext = mimetypes.guess_extension(content_type)
            if ext:
                filename += ext
        if not ext and link.url != geturl(resp):
            ext = os.path.splitext(geturl(resp))[1]
            if ext:
                filename += ext
        temp_location = os.path.join(temp_dir, filename)
        download_hash = _download_url(resp, link, temp_location)
    if link.md5_hash:
        _check_md5(download_hash, link)
    if only_download:
        _copy_file(temp_location, location, content_type, link)
    else:
        unpack_file(temp_location, location, content_type, link)
    if target_file and target_file != temp_location:
        cache_download(target_file, temp_location, content_type)
    if target_file is None:
        os.unlink(temp_location)
    os.rmdir(temp_dir)


def _get_response_from_url(target_url, link):
    try:
        resp = urlopen(target_url)
    except urllib2.HTTPError:
        e = sys.exc_info()[1]
        logger.fatal("HTTP error %s while getting %s" % (e.code, link))
        raise
    except IOError:
        e = sys.exc_info()[1]
        # Typically an FTP error
        logger.fatal("Error %s while getting %s" % (e, link))
        raise
    return resp

class Urllib2HeadRequest(urllib2.Request):
    def get_method(self):
        return "HEAD"
